This proposal describes a series of experiments aimed at identifying and defining specific mechanisms regulating the growth of the craniofacial complex. Previous experiments by our research group have demonstrated the relationship between form and function in the facial regions of both growing and non-growing individuals. By using experimental models, we are able to conduct research in a controlled environment so that specific regulatory mechanisms can be more fully understood. In this proposal, a series of experiments are described, the purpose of which is to define the role of specific cartilaginous, periosteal, dentitional, neuromuscular and neurotrophic factors which are active in the growth and development of the craniofacial region. A more complete knowledge of the regulatory mechanisms involved in facial growth is essential if we are to improve our understanding of normal growth processes and if we are to correct and control abnormal growth patterns encountered in human patients.